Spring dampened shedding device

ABSTRACT

A shedding device in a jacquard loom, having a heddle with a retracting spring rigidly anchored in the loom or to the floor for urging the heddle to a lower shed forming position. To suppress the development of resonance in the spring, a core element is provided, which contacts the inside of the spring at points spaced apart from one another and forces the spring to take a course which deviates from the rectilinear. As a result, friction forces that contribute to damping the spring motion are created between the spring and the core element.

FIELD OF THE INVENTION

The present invention relates generally to weaving looms, and moreparticularly to a spring controlled drive for reciprocating the heddleof such weaving looms.

BACKGROUND OF THE INVENTION

In weaving looms, and particularly in jacquard looms, heddles are movedin one direction while being pulled by a spring in the other direction.Generally, the heddle is moved by the spring to form the lower shed. Thespring is anchored at its opposite end in stationary fashion in the loomor to the floor and keeps a harness cord and the heddle under tensionduring their operation.

Like any spring-elastic system, the assembly comprising the spring,heddle and harness cord also exhibits a resonance phenomena, includingthe propagation of undulations that pass through the linear system. Thenatural resonance of the system does not matter, as long as the rate ofmotion of the heddle is low compared to the resonant frequency. However,at the moment when the rate of motion of the heddle reaches the range ofthe resonant frequency, unwanted undulations occur in the spring. Theundulations are induced in the spring by the motion of the heddle, andthey travel toward the fixed end, where they are reflected and run backtoward the heddle.

Under unfavorable circumstances, the heddle can even lose tension, sincethe returning undulation in the connection between the spring and theheddle has a phase relationship counter to the motion initialized by themotion of the harness cord.

The resonance inside the spring also causes increased mechanical stressand premature breakage.

To damp the resonance in the spring, it is known from European PatentDisclosure EP 0 678 603 to provide the lower spring fastening point witha damping device. The lower spring fastening point comprises a plasticmolded part with a threaded peg onto which the helical spring isscrewed. The threaded peg has two legs on its free end that arespring-elastically moveable counter to one another and which protrudeinto the interior of the spring and press against the spring. On the endremote from the threaded peg, the two legs are joined together again andmerge with two further legs, which form an open fork.

It has been found that this type of spring damping is not unproblematic.If the contact pressure with which the legs act against the inside ofthe spring windings is too hard, no effective damping action occurs.Instead, the arriving undulations are reflected, largely unattenuated,at those points where the legs touch the inside of the spring.Conversely, if the contact pressure is too low, once again adequatedamping does not ensue. This unfavorable phenomenon is reinforced by thefact that the spring elasticity of the plastic can exhibit fatigue andis also temperature-dependent. Furthermore, it is difficult to threadthe open ends of the legs into the spring.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a loom sheddingdevice in which the retraction spring is anchored in a manner that moreeffectively dampens undesirable resonating propagations of the springduring operation of the shedding device.

As in the prior art, the heddle of the shedding device according to theinvention is kept taut between the harness cord and the helical spring.The end of the helical spring remote from the heddle is anchored instationary fashion. To achieve the desired damping, there is a dampingelement, which at least at a plurality of spaced-apart points is incontact with the helical spring and imposes a nonrectilinear course orshape to the originally straight helical spring. In this way, thehelical spring is in contact with the damping element at points spacedapart from one another. The contact force of the helical spring on thedamping element is determined by the intrinsic elasticity of the springand by the extent of the deflection. Conversely, the elasticity of thedamping element plays practically no role.

Because of the essentially point-type contact between the helical springand the damping element, some of the vibration energy at every point ofcontact can be converted into friction. The reflections of themechanical undulation that occur at the contacting points arequantitatively too slight to be capable of generating a significantreturning undulation that could cause springs to break. Between thecontacting points, conversely, the spring extends somewhat freely.

Since the extent to which the spring is pressed against the dampingelement depends only on the geometric extent of the nonrectilinearcourse that the helical spring assumes because of the damping element,very precisely replicable contact pressures are achieved. The modulus ofelasticity of the steel helical spring is far less temperature-dependentthan the modulus of elasticity of plastic, and moreover, the modulus ofelasticity also varies less over time.

Finally, practically no permanent deformation occurs in the steel springsince it gradually adapts to the nonrectilinear course of the dampingelement. The damping element, conversely, compared to the resilience ofthe helical spring, need not have any elasticity at all. Relative to theforce exerted by the helical spring, the damping element can besufficiently rigid that it is not pressed into a different shape by thehelical spring. In this way, it is possible to generate very precisereplicable contact pressures and thus very precise replicable frictionforces between the spring and the damping element.

In particular, it is possible to cause the damping element to interactwith the helical spring over a comparatively very long distance.Moreover, it is possible for the extent of deformation, that is, thewavelength and/or the amplitude that the damping element imposes on thehelical spring, to vary over the length of the damping element. In thisway, increasing damping or bunching of the vibration can be attained. Inthe direction of the heddle, the damping element is initially deformedrelatively little out of the rectilinear course, and the deformationincreases toward the anchoring end of the helical spring. Very gooddamping with only very slight dispersion is attained at the dampingelement.

The damping element is preferably a linear core element, which isdisposed in the helical spring. This saves additional space for thedamping element because it is disposed at a location that is necessarilypresent anyway.

To achieve the desired deformation, the core element can have a courseor shape that deviates from a rectilinear course. Another option is touse an intrinsically rectilinear core element, which has discretelydistributed, bumplike protrusions or humps spaced apart from oneanother, with which the desired nonrectilinear course is imposed on thehelical spring. The diameter in the region of the protrusion or hump isless than the inside width of the helical spring.

The core element with a nonlinear course essentially has a cylindricalconfiguration with an undulating course or shape. The undulationsexpediently define a straight regression line, so that on average, astraight course of the spring comes about.

The undulating course can occur because the core element forms a helix,or because the core element forms undulations that are located in thesame plane.

In each case, a projection of the core element on a plane generates aband with an undulating course, whose width is equivalent to thediameter of the core element and whose undulating nature essentiallymatches the undulating or helical course of the core element. Thedimensions of the undulating course are expediently defined at this bandcreated by projection in the plane. In the projection, the undulatingcourse can be seen to have an undulation depth, measured on one edge ofthe band, between a crest and a trough of between 0.1 and 3 mm. Themagnitude of this undulation rise depends on the ratio of diametersbetween the core element and the inside width of the helical spring andon how strongly the helical spring is deflected or is to be pressedagainst the core element. The spacings between the crest and trough canrange between 2 and 20 mm.

In the case where protrusions or humps are used, they can be disposedalong a helical line, or in the simplest case along a zigzag; that is,each two adjacent protrusions are located on opposite sides relative tothe core element. The spacing between protrusions is in the rangebetween 5 mm and 30 mm, and preferably between 5 mm and 20 mm.

The protrusions or humps preferably are integral with the core elementand can be formed on either by injection molding or in some other waydepending on the manner in which the core element is produced. Anotheroption is to create the humps by local deformation, such as by crimpingto form ears. This last option is attractive if the core elementcomprises a permanently deformable material, such as metal.

The length of the core element is such that at least one completeundulation with the above dimensions can be generated. The core elementcan rest loosely in the helical spring or can be joined solidly to thelower anchoring means.

Thermoplastics such as polyamide, polyethylene and polyurethane, or suchother materials as metal, ceramic, pressure-setting plastics orvulcanizable materials, can be considered as material for the coreelement.

The shedding device of the invention is preferably employed in jacquardlooms. Because of its very good damping action and the little spacerequired, however, the arrangement according to the invention is notlimited to jacquard looms, but can also be employed in normal looms forproducing unpatterned woven fabrics, or heddle machines. Accordingly,the shedding device is also for instance a heddle machine, a jacquardloom, or a comparable drive device for setting the heddles in motion.

To connect the heddle to the helical spring, the heddle can be providedon the applicable end of the heddle shaft with a plastic molded part,which by way of example has a thread that can be screwed into thehelical spring. Connecting the helical spring to the lower or upperanchoring element can be done as in the prior art.

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of an illustrated shedding device in accordancewith the invention;

FIG. 2 is an enlarged side elevational view of the core element of theillustrated shedding device;

FIG. 3 is a depiction of an upper connection between a heddle shaft anda retracting spring of the illustrated device;

FIG. 4 is an enlarged view of an alternative embodiment of core elementformed with lateral protrusions;

FIG. 5 is a transverse section of the core element shown in FIG. 4,taken at the level of one of the protrusions;

FIG. 6 is an enlarged view of another embodiment of core element inwhich protrusions are created by local deformation of the core element;and

FIG. 7 is a transverse section of the core element shown in FIG. 6 takenat the level of one of the protrusions.

While the invention is susceptible of various modifications andalternative constructions, certain illustrated embodiments thereof havebeen shown in the drawings and will be described below in detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific forms disclosed, but on the contrary, theintention is to cover all modifications, alternative constructions andequivalents falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now more particularly to FIG. 1 of the drawings, there isshown an illustrative shedding device in accordance with the inventionin a jacquard loom. The shedding device includes a drive device whichincludes a roller train 2 as illustrated. From the roller train 2, acollet cord secured to a collet floor 3 extends and changes into aharness cord 4 that passes between a glass grate or a guide floor 5. Theharness cord 4 travels on to a harness board 6, where it emerges at thebottom through a bore 7. On the lower end, that is, the end of theharness cord 4 that is remote from the roller train 2, a heddle 8 issecured. The heddle 8 has an eyelet or eye 9 for a warp thread 11. Fromthe eye 9, upper and lower heddle shafts 12, 13 extend, located on thesame straight line. The lower end of the lower heddle shaft 13 isconnected to a retracting spring 14, which is anchored at 15 to themachine frame or to the floor.

The motion of the roller train 2 is transmitted to the heddle 8 via theharness cord 4. As a result, the harness cord 4 is pulled upward, andthe eye 9 is pulled upward out of its neutral position to form the uppershed. This tenses the retracting spring 14 more strongly than in theneutral position of the heddle 8, which is equivalent to the closedshed. When the harness cord 4 is let down, the retracting spring 14pulls the heddle 8 downward to the same extent as the harness cord 4moves downward. As a result, the applicable warp thread 11 forms thelower shed.

As readily seen, the upward motion of the heddle 8 is a compulsorymotion, which is imposed rigidly by way of the harness cord 4, whichcannot stretch in the longitudinal direction. The opposite direction,conversely, is a motion brought about by the retracting spring 14 and inthis sense is only conditionally compulsory.

The configuration comprising the harness cord 4, heddle 8, warp thread11 and retracting spring 14 is a spring mass system that has one or moreresonant frequencies. At high machine speeds, the frequency at which theheddle 8 is moved out of the neutral position with the shed closed intothe position for the upper shed or into the position for the lower shedis approximately 10 Hz. These frequencies, which are imposed by thedrive system 1, are on the order of magnitude of the resonantfrequencies of the entire system, or the resonant frequency of partialsystems. Moreover, harmonics also occur, and at these frequencies,undulations develop in the linear configuration between the harnessboard 6 and the anchoring point 15 in the retracting spring 14, and ifappropriate countermeasures are not taken, they are reflected at theanchoring point 15 and become standing waves in the retracting spring14. As a result, the retracting spring 14 is extremely severely stressedat certain points and tends toward breakage. In accordance with theinvention, a retracting spring of the shedding device is anchored in amanner that more effectively dampens resonating propagations in thespring during operation of the shedding device. In the illustratedembodiment, the lower end of the retracting spring 14 is connected to ananchoring element 16, as best depicted in FIG. 2, which in this case hasa rod-like form thread. The anchoring element 16 has an eyelet 17 on itslower end that can be secured to a suitable rail mounted in fixedfashion to the machine frame. An essentially cylindrical shaft 18extends from the eyelet 17 and is provided with a collar 19 on its upperend. A male-threaded peg 21 extends above the collar 19, concentricallyto the shaft 18, onto which the spring is screwed. The male-threaded pegin this instance has a length equivalent to approximately ten springwindings. The retracting spring 14 is a cylindrical spring, wound ofcylindrical steel wire, in which the windings in the relaxed statetypically rest on one another.

On its free end, the threaded peg 21 changes into a core element 22,which as shown has a nonrectilinear course or shape formed with troughs23 and crests 24. It is deformed in such a way that the surface definedby the troughs and crests defines a plane. This means that in a sideview rotated 90°, compared to FIG. 2, the core element 22 has a straightcourse or length.

As can readily be seen, the trough 23 on the opposite side of the coreelement 22 leads to a crest, like the crest 24, which in thecorrespondingly opposite direction deforms the spring 14.

The core element 22 has a circular cross section at all points, and thediameter of the cross section is less, by about 5 to 30%, than theinside diameter of the helical spring 14. The diameter of the coreelement 22 can be constant over its length or can decrease toward thetip. The core element 22 preferably is injection-molded in one piecefrom plastic along with the threaded peg 21, shaft 18 and eyelet 17.Suitable plastics are polyamide, polyethylene, polyurethane, andpolyester.

The undulating course that the core element 22 is so pronounced that thetroughs and crests 23, 24 impose a corresponding course on the helicalspring. Hence, the helical spring 14 no longer extends rectilinearly inthe region of the core element but instead has a zigzag shape thatcorresponds to the core element 22, as represented by the dashed lines25 and 26. The lateral deflection of the spring 14 is lessened inaccordance with the difference in diameter between the outside diameterof the core element 22 and the inside width of the helical spring 14.

The form of the illustrated core element 22, as depicted in FIG. 2, isequivalent to a projection of the core element 22 onto a plane,specifically a projection in which the undulating band generated by theprojection has the greatest amplitude. If each of the boundary linesthus obtained is considered to be the course of a vibration, theamplitude of the vibration from tip to tip is about 0.1 to 3 mm, andpreferably 0.1 to 1 mm, while the wavelength of the vibration is betweenabout 4 and 40 mm; although both values can vary along the length of thecore element 22.

The amplitude of the undulating line, that is, the extent of lateraldeflection, can increase from the free end of the core element 22 to thethreaded peg 21. As a result, the windings of the spring 14 rest on thefirst crest of the core element with relatively lower lateral forcebecause it is not deformed as much as at a crest that is located closerto the threaded peg 21.

The connection between the lower heddle shaft 13 and the retractingspring 14 is shown in FIG. 3. As can be seen there, a plastic moldedpart 27 is formed onto the free end of the heddle shaft 13 andcorresponds in terms of its structure to the collar 19 of the anchoringelement 16. The plastic molded part in this instance forms a collar 28and also a threaded peg 29 that extends coaxially to the heddle shaft13. The threaded peg 29 has a male thread, which may be cylindrical ortapered, onto which the retracting spring 14 is screwed, as describedabove, until the end strikes the collar 28, as shown.

The mode of operation of the core element 22 as a damping member in thespring 14 is approximately as follows:

When an impact is introduced from the upper end of the retracting spring14 through the heddle 8, the impact travels as a longitudinal wave overthe taut retracting spring in the direction of the anchoring element 16.In normal operation, care is taken to assure that the spring windings ofthe retracting spring 14 will not rest on one another in any operatingsituation. As a result of the impact wave, however, such contact cancertainly occur.

In every case, the impact wave travels through the spaced apart windingsof the spring, which now correspondingly reach the core element 22.Between the applicable moving spring windings and the respective crest23, 24 of the core element, friction occurs. The friction converts theenergy of motion of the spring windings into heat and thus draws energyfrom the system. Excessive increases in amplitude caused by resonanceare effectively suppressed. In particular, the damping assures that animpact wave traveling in the direction of the threaded peg 21 will reachthe end of the helical spring 14 that is fixed to the threaded peg 21only in attenuated form and will cause a corresponding echo of reducedamplitude, which in turn is further attenuated in its return travelalong the core element.

In this way, the core element 22 effectively assures a suppression ofstanding waves on the retracting spring 14. The damping action by thecore element 22, whose total length is between 5% and 40%, preferably10% and 30%, of the retracting spring 14 that is taut in operation, alsoassures that longer-frequency waves are effectively damped in order tosuppress the development of standing waves whose wavelength is on theorder of magnitude of the taut spring.

For assembly reasons, the core element 22 preferably should integrallyjoin the threaded peg 21. However, there is no necessity to do so. Onthe contrary, for producing its damping action, the core element can beprovided at an arbitrary point. Alternatively, the core element 22 couldbe integrally connected to the anchoring member 27, by which the lowerheddle 13 is coupled to the retracting spring 14.

Another exemplary embodiment of a core element 22 is depicted in FIG. 4,which serves to impose a nonrectilinear course on the helical spring 14,and at the same time, only point contact comes about between the coreelement 22 and the helical spring 14 in generating the above-describeddamping action.

The core element 22 depicted in FIG. 3 comprises a straight shaft 31,whose diameter is markedly less than the inside cylindrical diameter ofthe helical spring 14. Bumplike extensions or humps 32 are located alonga helical line on the outside of the shaft 31. In this case, the bumpsor extensions 32 are offset from one another by 90° each; that is, inprojection, as shown in the cross section of FIG. 5, the result is afour-pointed star. Nevertheless, the greatest diameter in the region ofeach hump 32 is less than the diameter of the interior of the helicalspring 14. However, since the projection of two diametrically opposedextensions 32 onto a plane that intersects the axis of the shaft 31 at aright angle is greater than the diameter, the helical spring 14 isforced out of its intrinsic rectilinear shape into a shape in the formof a helical line.

The height of the hump 32, as measured in the radial direction relativeto the axis of the shaft 31, and the spacing of the extensions 32, asmeasured in the longitudinal direction of the shaft 31, define the forcewith which the helical spring 14 rests on the crests of the extensions32.

Still another alternative embodiment of a core element 22 is depicted inFIGS. 4 and 5, which again comprises a one-piece plastic molded partwith bumplike extensions 32 integrally formed thereon. Their axiallength in this case is less than their axial spacing from one another.Instead of integrally forming the bumplike protrusions 32 onto a plasticmolded part, alternatively as shown in FIG. 6, the core element 22 mayhave a shaft 31 originally in the form of a cylindrical metal wire withthe protrusions or humps 32 being formed therein by laterally crimpingthe starting material, so that the material is positively displacedradially outward with the cross section shown in FIG. 4. This creates“ears” which protrude radially past the contour of the originallycircular cross section. The effect is the same as is described above forthe exemplary embodiment of FIG. 2.

1. A shedding device (1) for a loom, such as a jacquard loom, comprisinga heddle (8) which includes an eyelet (9) from which heddle shafts (12,13) extend on diametrically opposed sides, a drive device forlongitudinally moving said heddle (8), one of said heddle shafts (12)being coupled with said drive device (2) and the other of said heddleshafts (13) having a connecting device (27), an elongated helical spring(14) having one end mounted on said connecting device (27) for movingsaid heddle (8) in a retracting direction, an anchor (16) fixedlyanchoring the other end of the helical spring (14); and a longitudinallyextending damping element (22) having a nonrectilinear shape defined bya plurality of longitudinally spaced protrusions in contact with saidhelical spring at at least a corresponding plurality of longitudinallyspaced-apart points for forcing and causing the helical spring to take anonrectilinear shape along an elongated length thereof.
 2. The sheddingdevice of claim 1 in which said damping element (22) is a longitudinallyextending core element disposed in the helical spring (14).
 3. Theshedding device of claim 2 in which the diameter of the core element(22), as measured at the height of a given protrusion (32) is less thanthe inside diameter of the helical spring (14).
 4. The shedding deviceof claim 2 in which said protrusions are defined by an undulating shapeof the core element (22).
 5. The shedding device of claim 2 in whichsaid core element (22) is shaped in undulating fashion with saidprotrusions defined by undulations located in common planes.
 6. Theshedding device of claim 2 in which said core element (22) has a crosssection that is substantially constant over the length thereof.
 7. Theshedding device of claim 2 in which said core element (22) has planarsides with two edges parallel to one another in an undulating line, andthe undulating line has an amplitude, measured between a trough (23) anda crest (24), that is between 0.1 and 3 mm.
 8. The shedding device ofclaim 7 in which a spacing between a crest (24) and a trough (23) of theundulating line is between 2 and 20 mm.
 9. The shedding device of claim7 in which the undulating line defined by the core element (22) includesat least one complete undulation.
 10. The shedding device of claim 3 inwhich said protrusions (32) protrude alternately from different sides ofthe core element (22).
 11. The shedding device of claim 3 in which saidprotrusions (32) are integral with the core element (22).
 12. Theshedding device of claim 3 in which said protrusions (32) are created bylocal crimping of the core element (22).
 13. The shedding device ofclaim 3 in which said protrusions (32) have a spacing from one anotherof between 5 mm and 30 mm.
 14. The shedding device of claim 3 in whichsaid protrusions (32) have a spacing from one another of between 5 mmand 20 mm.
 15. The shedding device of claim 2 in which said core elementis made of a thermoplastic material.
 16. The shedding device of claim 15in which said shedding device is made of one of polyamide, polyethylene,or polyurethane.
 17. The shedding device of claim 2 in which said coreelement is made of a metal, ceramic, pressure setting plastic orvulcanized material.
 18. The shedding device of claim 1 in which saiddamping element (22) is integrally formed with one of the anchoringdevice (16) or connecting device (12).
 19. The shedding device of claim1 in which said connecting device (27) is a plastic molded part at anend of that other heddle shaft (13).
 20. The shedding device of claim 18in which the connecting device (27) has a thread (29).
 21. The sheddingdevice of claim 1 in which such anchoring device (16) has a thread (21).22. The shedding device of claim 18 in which said thread (29) comprisesa male threaded section.
 23. The shedding device of claim 21 in whichsaid thread (21) comprises a male threaded section.
 24. The sheddingdevice of claim 2 in which said core elements (22) have discreteprotrusions spaced from one another along the length thereof, and saidcore element tapers inwardly toward a free end thereof.
 25. The sheddingdevice of claim 24 in which said core element (22) has a diameter over alength thereof that is at least as great as the inside diameter of thehelical spring (14) and which decreases in diameter at a free end to adiameter less than the inside diameter of said helical spring (14). 26.The shedding device of claim 1 in which said helical spring (14) is ahelical tension spring in which individual windings of the spring reston one another in a relaxed state.
 27. The shedding device of claim 1 inwhich said helical spring (14) is made of steel thread.
 28. A sheddingdevice (1) for a loom, such as a jacquard loom, comprising a heddle (8)which includes an eyelet (9) from which heddle shafts (12, 13) extend ondiametrically opposed sides, a drive device for longitudinally movingsaid heddle (8), one of said heddle shafts (12) being coupled with saiddrive device (2) and the other of said heddle shafts (13) having aconnecting device (27), a helical spring (14) having one end mounted onsaid connecting device (27) for moving said heddle (8) in a retractingdirection, an anchor (16) fixedly anchoring the other end of the helicalspring (14); and a helical shaped damping core element (22) disposed insaid helical spring (14) in contact with said helical spring at at leasta plurality of spaced-apart points for forcing and causing the helicalspring to take a nonrectilinear shape.
 29. A shedding device (1) for aloom, such as a jacquard loom, comprising a heddle (8) which includes aneyelet (9) from which heddle shafts (12, 13) extend on diametricallyopposed sides, a drive device for longitudinally moving said heddle (8),one of said heddle shafts (12) being coupled with said drive device (2)and the other of said heddle shafts (13) having a connecting device(27), a helical spring (14) having one end mounted on said connectingdevice (27) for moving said heddle (8) in a retracting direction, ananchor (16) fixedly anchoring the other end of the helical spring (14);and a damping core element (22) disposed in said helical spring (14)having protrusions disposed along a helical line in contact with saidhelical spring at at least a plurality of spaced-apart points forforcing and causing the helical spring to take a nonrectilinear shape.